Playback device and storage medium

ABSTRACT

A playback device ( 1 ) and a storage medium ( 10 ) for storing audio data make it possible to increase the audio data volume that may be stored on such a storage medium without increasing the data density. To this end, the audio data compressed according to at least one compression method is stored on the storage medium ( 10 ). The playback device ( 1 ) includes a drive ( 5 ) for storage media ( 10 ) and a scanning device ( 20 ) for audio data recorded on a storage medium ( 10 ) inserted into the drive ( 5 ). The playback device ( 1 ) furthermore includes a control ( 15 ) that checks whether the data read is compressed. The playback device ( 1 ) furthermore includes a decompression device ( 25 ) that carries out decompression of the audio data if the audio data is compressed.

BACKGROUND INFORMATION

[0001] The present invention relates to a playback device and a storage medium according to the definition of the species of the independent claims.

[0002] Storage media in the form of audio CDs (compact disks), on which audio data is stored, are already known. Furthermore, playback devices in the form of audio CD players are known, each of which include a drive for playing audio CDs and an optical read head for reading audio data recorded on an audio CD inserted into the drive.

ADVANTAGES OF THE INVENTION

[0003] The playback device according to the present invention and the storage medium according to the present invention having the features of the independent claims have, in contrast, the advantage that the audio data may be stored on the storage medium in compressed form according to at least one compression method, and that the playback device includes a control, which examines whether the audio data read from the storage medium inserted into the drive is compressed, the playback device having a decompression device, which carries out a decompression of the audio data if the audio data is compressed. In this manner, the capacity of a storage medium for storing audio data, for example of an audio CD, can be greatly increased without having to enlarge the recording or writing density of the audio data on the storage medium. In this manner, conventional methods for the manufacture of storage media for audio data can be maintained despite increased storage capacity for the audio data. Moreover, the recording length for such a storage medium may be extended considerably.

[0004] Through the measures cited in the subclaims, advantageous refinements of and improvements on the playback device specified in the independent claim 1 are possible.

[0005] It is particularly advantageous that the control determines the type of compression of the audio data and that the decompression device decompresses the audio data depending on the type of compression determined. In this manner, it is possible to implement a playback device for storage media with compressed audio data that offers decompression for various types of audio data compression and is consequently particularly versatile.

[0006] A further advantage exists in that the playback device includes a memory, in which the control stores the audio data of the storage medium read by the scanning device and detected as compressed before it is relayed on to the decompression device. In this manner, it is possible to achieve buffering of the compressed audio data read, which is necessary in order to adapt an adjustment of the audio data volume read from the storage medium per time unit to an audio data volume per time unit required for the further processing, for example, for acoustic playback of the audio data.

[0007] A further advantage exists in that the control, upon detecting compressed audio data, causes the scanning device to read the audio data in portions, particularly track by track, from the storage medium. In this manner, overflow of the memory is prevented since, due to the compression of the audio data, the audio data volume read per time unit is greater than the audio data volume per time unit necessary for the further processing of the audio data.

[0008] A further advantage exists in that the control, upon detecting uncompressed audio data of the scanned storage medium, feeds this audio data directly or via a digital/analog converter, particularly for relaying to a playback apparatus. In this manner, the playback device is also usable for playing back storage media with uncompressed audio data and is consequently even more versatile.

DRAWING

[0009] An embodiment of the present invention is illustrated in the drawing and is explained in greater detail in the following description.

[0010]FIG. 1 shows a block diagram of a playback device according to the present invention.

[0011]FIG. 2 shows a flow diagram for a control of the playback device according to the present invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

[0012]FIG. 1 shows a playback device 1 for playing back storage media 10 having audio data recorded on storage media 10. Storage media 10 may, for example, be optical and/or magnetic storage media, in which the audio data is optically and/or magnetically recorded. Playback device 1 furthermore includes a drive 5 into which such a storage medium 10 can be inserted. Drive 5 includes a scanning device 20 for reading audio data recorded on the storage medium 10 inserted into drive 5. Drive 5 may, for example, be an optical and/or magnetic drive, depending on whether the audio data is optically or magnetically stored on storage medium 10. Scanning and reading of the audio data of storage medium 10 takes place optically or magnetically as appropriate through scanning device 20. If drive 5 is an optical drive with optical scanning device 20, playback device 1 may, for example, be implemented as an audio CD player for playing back storage media 10 designed in the form of audio CDs. If drive 5 is a magnetic drive with a magnetic scanning device 20, playback device 1 may in this case be designed, for example, as a cassette recorder for playing back storage media 10 designed in the form of audio cassettes. These audio cassettes may be analog or digital recording media.

[0013] In the following description, it is assumed, for example, that playback device 1 is designed as an audio CD player. Scanning device 20 is then designed for optical scanning and reading a storage medium 10 in the form of an audio CD using a laser beam 45. In this case, drive 5 can be described as an optical drive. On audio CD 10, the audio data is stored in tracks concentrically to a center of the audio CD 10 and is read by scanning device 20 using laser beam 45. The audio data read in this manner is fed to a control 15. Control 15 in turn controls scanning device 20 with corresponding control commands. Moreover, control 15 is connected to a memory 30 and a decompression device 25. Memory 30 and decompression device 25 are likewise connected to one another. Decompression device 25 is connected, both via a digital/analog converter 35 and directly, to an audio interface 40 of playback device 1, to which circuits or devices for further processing of the audio data read from audio CD 10 are connectable. This may, for example, be an acoustic playback device in the form of one or several amplifiers and one or several loudspeakers connected thereto. However, the audio data read may also be appropriately processed further in audio CD player 1 itself and these audio signals are reproducible on a playback apparatus of audio CD player 1, for example.

[0014] Audio interface 40 consequently includes a digital output 50, which is directly connected to decompression device 25, and an analog output 55, which is connected to decompression device 25 via digital/analog converter 35. Decompression device 25 may also be designed as a digital signal processor or as a part of such a digital signal processor. A flow diagram for the operation of control 15 is shown in FIG. 2. At a program point 100, digital audio data stored on audio CD 10 inserted into drive 5 is read by scanning device 20 using laser beam 45 and relayed to control 15. Afterwards, the program branches off to point 105. At program point 105, control 15 checks whether the digital audio data read is compressed. If this is the case, the program branches off to point 110, otherwise, the program branches off to point 125. The audio data can be stored on audio CD 10 according to at least one compression method, for example according to the MP3 process (MPEG layer-3; MPEG=Motion Picture Expert Group). In this manner, more audio data can be saved on audio CD 10, with an unmodified, conventional storage density, than is possible without compression. In the MP3 format, for example, nine times as much data can be saved on audio CD 10 than without compression. Here, the various compression methods represent various types of compression. At program point 110, control 15 determines the type of the compression of the audio data read and reports this type of compression to decompression device 25 for selecting the decompression algorithm suitable for the decompression of this audio data. In the case of the compression according to the MP3 method, cited as an example, this method may take place either through analysis of the data format used for the compression or, in a much simpler fashion, through analysis of the file name extension used for the data stored on audio CD 10. In the case of the compression according to the MP3 method, this extension is “MP3”, for example. The file name may additionally be displayed on a display device of audio CD player 1 not shown, and for instance, indicate a music title. Each music title on audio CD 10 could be stored here in file form with the corresponding file name. Afterwards, the program branches off to point 115, in which control 15 controls scanning device 20 in such a way that it reads a specified audio data volume from audio CD 10, the audio data read being stored temporarily in memory 30. Here, for example, control 15 may control scanning device 20 such that it reads all the audio data of a data track of audio CD 10 and this audio data read may be stored temporarily afterwards in memory 30. Subsequently, the program branches off to point 120, in which decompression device 25 step-by-step requests the audio data stored in memory 30 through corresponding memory addressing, whereupon the addressed audio data is transferred by memory 30 to decompression device 25 and is decompressed there using the selected decompression algorithm. Afterwards, the program branches off to point 125. At program point 125, decompression device 25 hands over the decompressed audio data both to digital/analog converter 35 and directly to digital output 50 of audio interface 40. Digital/analog converter 35 converts the digitally decompressed audio data into analog audio data and hands it over to analog output 55 of audio interface 40. In the event that in program point 105 it is determined by control 15 that the audio data read is not compressed, the audio data read is transparently passed by control 15 through decompression device 25, i.e., no decompression algorithm is selected for decompression device 25, so that the audio data read is delivered either directly and in digital form to digital output 50, or after digital/analog conversion through digital analog converter 35, in analog form to analog output 55 at program point 125. Afterwards, the program branches off to point 130. At program point 130, control 15 checks whether all the audio data to be read was already read from audio CD 10. If this is the case, the program is exited; otherwise the program branches back to point 100.

[0015] At program point 130, control 15 checks in the case where the audio data is stored in a compressed manner on audio CD 10, whether all the audio data stored in memory 30 has already been decompressed by decompression device 25 and relayed to audio interface 40. Control 15 causes a new audio data volume, for example a new data track, to be read from audio CD 10 by scanning device 20 and relayed to memory 30 only when the audio data previously stored in memory 30 has been completely decompressed by decompression device 25 and relayed to audio interface 40. In this manner, data loss due to overflow of not yet decompressed audio data in memory 30 is prevented. Thus, control 15, depending on the processing status of the audio data that is currently in memory 30, specifies the times for the renewed reading of an audio data volume from audio CD 10 if compressed audio data is stored on audio CD 10. In the conventional case of uncompressed audio data stored on audio CD 10, reading in portions of the audio data stored on audio CD 10 is not necessary, however, since no temporary storage of this audio data in memory 30 and no decompression in decompression device 25 are necessary, such uncompressed audio data can be continuously read by scanning device 20 and relayed in the described manner to audio interface 40.

[0016] Audio data compressed according to various compression methods may be stored on audio CD 10. The types of compression used may be specified in this context in a lead-in area of audio CD 10 and collected there initially before control 15 starts reading the audio data. Here, the data tracks of audio CD 10 on which the audio data is compressed can be specified, along with the compression algorithm or compression method used. Here, data tracks or data sectors having compressed audio data as well as those having uncompressed audio data may also be provided on audio CD 10. Here, the uncompressed audio data is, as described, relayed in a transparent manner to audio interface 40 through decompression device 25. The amount of audio data of the compressed audio data to be stored in memory 30 may be selected by control 15 such that the corresponding audio data is all compressed according to the same compression method. Decompression device 25 may then use the same decompression algorithm or the same decompression method for the decompression of all audio data stored in memory 30. In storing audio data in memory 30, which is compressed according to various compression methods, control 15 must control decompression device 25 in such a way that it decompresses the audio data stored in memory 30, each time using the correct decompression method. Since control 15 knows the data sectors of audio CD 10 in which the audio data is stored using the various compression methods, it may store the audio data of a given amount of audio data to be read by scanning device 20, depending on the compression method used, into differently addressed memory areas of memory 30 and inform decompression device 25 of the allocation of the decompression method to be used to these memory areas of memory 30, so that decompression device 25 may decompress the audio data stored in the various memory areas of memory 30 with the appropriately allocated decompression algorithm.

[0017] Finally, at digital output 50 and at analog output 55, the compression method used to compress the audio data relayed there or whether the audio data present on audio CD 10 is compressed at all is no longer known. 

What is claimed is:
 1. A playback device (1) having a drive (5) for storage media (10) and a scanning device (20) for reading audio data recorded on a storage medium (10) inserted into the drive (5), having a control (15) that checks whether the audio data read is compressed, and that determines the type of compression of the audio data, having a decompression device (25), which carries out a decompression of the audio data if the audio data is compressed, having a memory (30), in which the control (15) stores the audio data of the storage medium (10) read by the scanning device (20) and detected as compressed, before it is relayed to the decompression device (25), wherein the amount of audio data read is stored in differently addressed memory areas of the memory (30) depending on the compression method used.
 2. The playback device (1) according to claim 1, wherein the control (15) determines the type of compression of the audio data, and the decompression device (25) decompresses the audio data depending on the type of compression that has been determined.
 3. The playback device (1) according to claim 1 or 2, wherein the control (15), upon detecting compressed audio data, causes the scanning device (20) to read the audio data in portions, in particular track by track, from the storage medium (10).
 4. The playback device (1) according to claim 3, wherein the control (15) of the scanning device (20) specifies the times for reading in portions.
 5. The playback device (1) according to one of the preceding claims, wherein the control (15) feeds the decompressed audio data directly or via a digital/analog converter (35) to an audio interface (40), particularly for relaying to a playback aparatus.
 6. The playback device (1) according to one of the preceding claims, wherein the control (15), upon detecting uncompressed audio data of the scanned storage medium (10), feeds this audio data directly or via a digital/analog converter (35) to an audio interface (40), particularly for relaying to a playback apparatus.
 7. The playback device (1) according to one of the preceding claims, wherein the decompression device (25) is designed as a digital signal processor.
 8. A storage medium (10) for storing audio data, in which the audio data stored on the storage medium is compressed according to various compression methods, the CD furthermore storing information about which data areas contain data stored according to which compression method. 